The present invention relates to a method of, and apparatus for, controlling an automatic step-wise transmission system for automobiles, and, more particularly, to a method of, and apparatus for, controlling the automatic step-wise transmission system to suppress a gear-changing shock which is caused by the hydraulic pressure control of various kinds of mechanisms in the gear-changing operation.
As one of the conventional methods of controlling the engine for automobiles, there has been proposed a controlling method wherein an offset value of a throttle-valve opening degree of a throttle valve when an engine key switch is turned on is sensed electronically, and the difference in the throttle-valve opening degrees also is adjusted. For example, such a controlling method is disclosed in Japanese KOKAI (Disclosure) Patent Application No. 53-105639 (laid open on September 13, 1978).
However, regarding such a conventional engine control method, no technical concept teaching the offset value of the throttle-valve opening degree for the controls, other than the engine control, has been proposed. The following reasons can be considered as causing the absence of such a technical idea.
That is, when the engine start key is turned on, the throttle-valve opening degree is not set always to "0". Further, since the throttle-valve opening degree which is not initialized to "0" is changed for the engine control, there is a problem such that it is difficult to measure the offset value. Alternatively, in the control of the automatic step-wise transmission system, an error present in the throttle-valve opening degree under the engine idling state may cause a problem, rather than when the throttle valve is closed fully. Therefore, the error present in the idling state of the engine requires correction.
There is an actual problem such that there are many fluctuations in adjustment of the throttle-valve opening degree. Particularly, the engine torque largely changes due to a slight difference of the opening degree. In addition, an electronic reading error of the throttle-valve opening degree or adjustment fluctuations near the idling speed range in which a car driver feels easily as a shock, become one of the causes of deterioration of the drivability of the vehicle.
The present invention solves the foregoing problems, and therefore an object of the invention is to provide a method of controlling an automatic step-wise transmission system in which the gear-changing shock based on the adjustment error of the throttle-valve opening degree, or the error due to an aging effect of the sensor to detect the throttle-valve opening degree, can be suppressed. Particularly, it is possible to emphasize the suppressing and controlling effects of the shock which can be felt most easily as a gear-changing shock at a position near the throttle-valve opening degree during the vehicle idling state and which occurs at a critical point in the control of the transmission system.
A further object of the invention is to provide an apparatus for controlling an automatic step-wise transmission system having the foregoing features.